How do you activate streetpass on Nintendo 3DS sound?

To activate StreetPass on your Nintendo 3DS, first ensure that your system is connected to Wi-Fi and that the StreetPass feature is enabled in the system settings. Go to "System Settings," then select "StreetPass Mii Plaza" and make sure the StreetPass function is turned on. You can also customize which games use StreetPass by adjusting the settings in each individual game. Once activated, your 3DS will automatically exchange data with other nearby 3DS systems when in sleep mode.